Several techniques have been proposed to asses hydration status in dialysis patient, among them measurement of bioimpedance and biochemical markers. Sonographic measurement of the inferior vena cava diameter (IVCD) is a method under investigation for assessing hydration status. It is available, inexpensive and efficient, yet operator-dependent. In a single-center, blinded and controlled trial it has been shown to improve clinical outcomes in patients receiving hemodialysis.